A dangerous heat wave has descended on much of California and the U.S. Southwest, with triple-digit temperatures expected along with a higher risk of wildfires. Officials opened cooling centers this week in Los Angeles and warned residents to avoid strenuous outdoor activities. California Gov. Gavin Newsom ordered state firefighting resources deployed in areas where blazes could ignite. The peak of the heat wave will hit Arizona on Thursday and Friday. Temperatures there could possibly reach 110 degrees Fahrenheit in the southern and western parts of the state.